1. Field of the Invention
This invention relates to wiring board in general, such as a film carrier, a flexible printed wiring board or a rigid printed wiring board, which are installed on a module, e.g. a liquid crystal panel. Further, this invention relates to a method of making those wiring boards and to a liquid crystal panel on which such a wiring board is installed.
2. Description of the Related Art
A film carrier board for a liquid crystal driver on a liquid crystal panel is conventionally made with one or more slits where the board is to be bent. Along the slit, the board material is absent, and the conductive patterns of copper or the like are exposed. If any external force is applied to this slit portion, an open circuit is likely to occur. Methods used to prevent this open circuit reinforce the mechanical strength of the conductive patterns or contemplate the bending angle and condition. Also, the bent portion of the board is sometimes divided into subdivisions to shorten the exposed length. After the film carrier board is bent and installed on a liquid crystal panel (Cf. FIG. 7), the bent portion is coated with a silicone-based resin or the like for reinforcement (Cf. FIG. 8).
The prior art techniques mentioned above have a number of problems. The method of subdividing the portion to be bent, since there is a limit to the slit size permissible on the board (min. 0.7 mm width, ordinarily), requires a longer bent portion if the number of subdivisions is increased. Therefore more film carrier has to be used, resulting in an increased cost of the film carrier. Compact bending is also given up. Reinforcing the bent portion with the resin after the film carrier is bent and installed on a liquid crystal panel requires considerable time and labor for resin application and curing, which incurs a cost increase.